<!DOCTYPE html>
<html>
	<head>
		<title>number falls</title>
	</head>
	<body>
		<canvas id="canvas"></canvas>
		<style type="text/css">
			body {
				margin: 0;
				padding: 0;
				overflow: hidden;
			}
		</style>
		<script type="text/javascript">
			var canvas = document.getElementById('canvas');
			var ctx = canvas.getContext('2d');
			var texts = '0123456789'.split('');
			var fontSize = 12;

			canvas.height = window.screen.height;
			canvas.width = window.screen.width;

			var columns = canvas.width / fontSize;
			var drops = [];

			for (var x = 0; x < columns; x++) {
				drops[x] = 1;
			}

			function draw() {
				//透明 -> 不透明
				ctx.fillStyle = 'rgba(0, 0, 0, 0.05)';
				ctx.fillRect(0, 0, canvas.width, canvas.height);
				//文字
				ctx.fillStyle = '#0F0';
				ctx.font = fontSize + 'px arial';

				//逐行输出文字
				for (var i = 0; i < drops.length; i++) {
					//texts中随机取一个数
					var text = texts[Math.floor(Math.random() * texts.length)];

					ctx.fillText(text, i * fontSize, drops[i] * fontSize);
					if (drops[i] * fontSize > canvas.height || Math.random() > 0.95) {
						drops[i] = 0;
					}
					drops[i]++;
				}
			}
			setInterval(draw, 33);
		</script>
	</body>
	<html>
